Fabia Mk2 - Amplifier Wiring

Can anyone help please?

I want to fit a combined sub/amplifier in my boot.

Ive sorted the speaker cabling from the back of the “Dance” head unit

The problem im

having is finding a suitable supply/connection for the main power.

Obviously direct power from the battery would be good, but having the 1.9 Diesel engine, I can’t see enough of the firewall to see where the wiring comes in?

Is there an easier place to pick

up a power feed?

Any help and pointers would be appreciated